Elevated pulmonary vascular resistance (PVR) and pulmonary hypertension (PH) are high risk factors for early graft failure in orthotopic heart transplantation (oHTx). The need for an oversized donor in patients with elevated PVR aggravates the shortage of suitable donor organs. To decrease the elevated PVR to values suitable for orthotopic heart transplantation prostaglandin E1 (PGE1) was administered in 11 patients (11 male, mean age 49.2 years, mean dosage 35 ng/kg per min over 6-8 days). Ten days after the discontinuation of the PGE1 therapy, recatheterization was done. All haemodynamic data were determined by right heart catheterization using a Swan Ganz catheter and thermodilution technique before, and 10 days after, PGE1 treatment. The Wilcoxon signed ranks test was used for statistics. PVR significantly decreased in all patients (5.5 to 2.8 Wood units, P < 0.005). All patients were considered to be suitable for oHTX and put on the waiting list. At the time of writing, in eight of these patients (eight male, mean age 49.6 years; four ischemic, four dilatative CMP) oHTX had been successfully performed. No right ventricular failure occurred in the postoperative phase. These results sugest that long-term moderation of elevated PVR by PGE1 therapy weeks or months before transplantation enables oHTX in patients with elevated PVR.